Integrated complementary push-pull B final stage

• US 4,879,522 A
• Filed: 08/12/1988
• Issued: 11/07/1989
• Est. Priority Date: 08/22/1987
• Status: Expired due to Fees

• Current Assignee: Telefunken Electronic GmbH
• Original Assignee: Telefunken Electronic GmbH
• Inventors: Mattfeld, Johann
• Primary Examiner(s): MOTTOLA, STEVEN J
• Application Number:
  US07/231,528
• Time in Patent Office: 452 Days
• Field of Search: 330/263, 330/269, 330/267, 330/268, 330/307, 330/310, 330/311
• US Class Current: 330/263
• CPC Class Codes: H03F 3/3066 the collectors of complementary power transistors being connected to the output

Abstract

To actuate a complementary push-pull class B final stage complementary driver transistors are provided whose emitters are electrically interconnected and connected to the collectors of the two final stage transistors via a filter section. This filter section is not integratable into the rest of the circuit on account of the high capacitance value of the capacitor. To permit design of this complementary push-pull class B final stage as an integrated circuit the filter section is replaced according to the invention by a circuit arranged between the emitters of the driver transistors and ground and having dynamic low impedance and being designed such that the operating voltage drops by about half across the integratable circuit.

Claims

1. A complementary push-pull class B final stage having first and second complementary driver transistors and having third and fourth complementary driver transistors whose emitters are directly interconnected,

wherein an integratable circuit is disposed between the connected emitters of the third and fourth driver transistors and an operating voltage

, the integratable circuit having dynamic low impedance such that about half of the operating voltage drops across the integratable circuit, and wherein the integratable circuit includes:

(a) fifth and sixth complementary transistors whose emitters are connected together and linked to the connected emitters of the third and fourth complementary transistors, and whose collectors are connected respectively to first and second terminals of the operating voltage source,

(b) a first resistor arranged between said first terminal of the operating voltage source and the base of the fifth transistor,

(c) a second resistor disposed between the second terminal of the operating voltage source and the base of the sixth transistor, and

(d) two diodes connected in series and oriented in the conducting direction with regard to the operating voltage, for connecting the bases of the fifth and sixth complementary transistors.

2. A complementary push-pull class B final stage having first and second complementary driver transistors and having third and fourth complementary driver transistors whose emitters are directly interconnected,

wherein an integratable circuit is disposed between the connected emitters of the third and fourth driver transistors and an operating voltage source, the integratable circuit having dynamic low impedance such that about half of the operating voltage drops across the integratable circuit, and wherein the integrated circuit

comprises:

(a) an operational amplifier having an output which is connected together with the connected emitters of the third and fourth complementary driver transistors and whose inverting input is connected to the output of the operational amplifier via a first resistor , and

(b) two substantially identically sized second and third resistors connected in series across the terminals of the operating voltage source, and whose common connection is linked to the non-inverting input of the operational amplifier.

3. A complementary push-pull class B final stage having first and second complementary driver transistors and having third and fourth complementary driver transistors whose emitters are directly interconnected,

wherein an integratable circuit is disposed between the connected emitters of the third and fourth driver transistors and an operating voltage source, the integratable circuit having dynamic low impedance such that about half of the operating voltage drops across the integratable circuit, and wherein the integratable circuit includes:

(a) fifth and sixth complementary transistors whose emitters are connected together and linked to the connected emitters of the third and fourth complementary transistors, and whose collectors are connected respectively to first and second terminals of the operating voltage source,

(b) one of a resistor and a current source arranged between the first terminal of the operating voltage source and the base of the fifth complementary transistor, and the other one of the resistor and the current source disposed between the second terminal of the operating voltage source and the base of the sixth complementary transistor, and

(c) two diodes connected in series and oriented in the conducting direction with regard to the operating voltage, for connecting the bases of the fifth and sixth complementary transistors.

4. A complementary push-pull class B final stage as claimed in claim 3, wherein the current source is disposed between the first terminal of the operating voltage source and the base of the fifth transistor, and the resistor is disposed between the second terminal of the operating voltage source and the base of the sixth transistor.